Numerical Investigation on Air Film Fusion of Pressure-Equalizing Exhaust around Shoulder Ventilation of Submarine-Launched Vehicle

In order to study the influence of pressure-equalizing exhaust at the shoulder of a submarine-launched vehicle on the surface hydrodynamic characteristics, this paper establishes a numerical calculation method based on the VOF multiphase flow model, the standard RNG turbulence model and the overset mesh technology; the method compares the fusion characteristics of the air film at the shoulder of the underwater vehicle, as well as the distribution of surface pressure along the vehicle’s axial direction. The results show that the approximate isobaric zone derived from air film fusion can greatly improve the hydrodynamic characteristics of the vehicle, and the number of venting holes determines the circumferential fusion time of the air film. The greater the number of venting holes, the sooner circumferential fusion starts.

Download Full-text

Numerical calculation of the resistance of catamarans at different distances between two hulls

E3S Web of Conferences ◽

10.1051/e3sconf/202128301008 ◽

2021 ◽

Vol 283 ◽

pp. 01008

Author(s):

Zhaochun Liu ◽

Xiufeng Zhang ◽

Yao Meng ◽

Linghong Wang

Keyword(s):

Numerical Calculation ◽

Model Test ◽

Calculation Method ◽

Empirical Formula ◽

Test Method ◽

Hydrodynamic Characteristics ◽

Model Parameters ◽

Ship Model ◽

Ship Model Test ◽

Numerical Calculation Method

For the design of high-speed catamarans, different distances between slices have obvious interference with the total resistance of the catamaran. In order to accurately predict the hydrodynamic characteristics of the catamaran and explore the interference of the chip spacing on the resistance prediction, this paper uses a combination of CFD calculations and empirical formulas to predict the ship model resistance under different chip spacings and calculate them. The result is compared with the empirical formula. The results of the ship model test and the results calculated by the empirical formula were used to verify the numerical calculation results. The results show that the resistance change trend is consistent, and the numerical calculation method is effective and feasible. Finally, the numerical calculation method is compared with the ship model test method, and the result is within the error range, which has certain reference value for the design and optimization of the catamaran model parameters.

Download Full-text

Research on Non-Uniform Wear of Liner in SAG Mill

Processes ◽

10.3390/pr8121543 ◽

2020 ◽

Vol 8 (12) ◽

pp. 1543

Author(s):

Wanrong Wu ◽

Haoran Che ◽

Qianhua Hao

Keyword(s):

Numerical Calculation ◽

Total Mass ◽

General Structure ◽

Axial Direction ◽

Wear Volume ◽

Sag Mill ◽

The Difference ◽

Numerical Calculation Method ◽

Steel Balls ◽

The Relationship

The numerical calculation method is used to analyze the wear of the liner of the general structure of a semi-autogenous mill in the axial direction, and the non-uniform wear of each area of the liner is studied to explore the reasons for said wear. The liner is divided into areas along the axial direction, and the discrete element method (DEM) is used to analyze the relationship between the wear volume of each area and the total mass of particles. The composition ratio of the rocks and steel balls in each area, and its relationship with time, are also studied. The results show that the total mass of the particles in the area has a significant effect on the wear of the liner. When the particles are affected by the conical end cover on both sides during the operation of the mill, they will be stratified along the axial direction. The particles with large masses will accumulate on both sides of the mill, and the particles with small masses will be concentrated in the middle of the mill. As a result, the difference between the density and impact energy of rocks and steel balls in each area is caused, and eventually, the mill liner appears to have non-uniform wear.

Download Full-text

Analysis of Hydrodynamic Characteristics in the Process of Autonomous Underwater Vehicle Docking

Volume 7: Ocean Engineering ◽

10.1115/omae2015-42323 ◽

2015 ◽

Cited By ~ 1

Author(s):

Xiaoxu Du ◽

Huan Wang

Keyword(s):

Drag Coefficient ◽

Autonomous Underwater Vehicle ◽

Simple Algorithm ◽

Underwater Vehicle ◽

Navier Stokes ◽

Hydrodynamic Characteristics ◽

Successful Operation ◽

Underwater Docking ◽

Computational Fluid Dynamics Cfd ◽

Volume Method

The successful operation of an Autonomous Underwater Vehicle (AUV) requires the capability to return to a dock. A number of underwater docking technologies have been proposed and tested in the past. The docking allows the AUV to recharge its batteries, download data and upload new instructions, which is helpful to improve the working time and efficiency. During the underwater docking process, unsteady hydrodynamic interference occurs between the docking device and an AUV. To ensure a successful docking, it is very important that the underwater docking hydrodynamics of AUV is understood. In this paper, numerical simulations based on the computational fluid dynamics (CFD) solutions were carried out for a 1.85m long AUV with maximum 0.2 m in diameter during the docking process. The two-dimensional AUV model without fin and rudder was used in the simulation. The mathematical model based on the Reynolds-averaged Navier-Stokes (RANS) equations was established. The finite volume method (FVM) and the dynamic structured mesh technique were used. SIMPLE algorithm and the k-ε turbulence model in the Descartes coordinates were also adopted. The hydrodynamics characteristics of different docking states were analyzed, such as the different docking velocity, the docking device including baffle or not. The drag coefficients of AUV in the process of docking were computed for various docking conditions, i.e., the AUV moving into the docking in the speed of 1m/s, 2m/s, 5m/s. The results indicate that the drag coefficient increases slowly in the process of AUV getting close to the docking device. When the AUV moves into the docking device, the drag coefficient increases rapidly. Then the drag coefficient decreases rapidly. The drag coefficient decreases with the increase of velocity when AUV enters the docking device. It was also found that the drag coefficient can be effectively reduced by dislodging the baffle of docking device.

Download Full-text

Numerical calculation method for estimaiton of vertical circulating flow and density current in two-layer model.

PROCEEDINGS OF COASTAL ENGINEERING JSCE ◽

10.2208/proce1989.36.204 ◽

1989 ◽

Vol 36 ◽

pp. 204-208 ◽

Cited By ~ 6

Author(s):

KAZUO MURAKAMI

Keyword(s):

Numerical Calculation ◽

Calculation Method ◽

Density Current ◽

Layer Model ◽

Two Layer Model ◽

Numerical Calculation Method

Download Full-text

Determination Method of Elasto-Plastic Correction Factor of TA16 Titanium Alloy Based On RCC-M Code Methodology

Journal of Pressure Vessel Technology ◽

10.1115/1.4049708 ◽

2021 ◽

Author(s):

Xuejiao Shao ◽

Juan Du ◽

Liping Zhang ◽

Hai Xie ◽

Jun Tian ◽

...

Keyword(s):

Stainless Steel ◽

Titanium Alloy ◽

Numerical Calculation ◽

Austenitic Stainless Steel ◽

Constitutive Model ◽

Correlation Coefficient ◽

Correction Factor ◽

Calculation Method ◽

Plastic Correction ◽

Numerical Calculation Method

Abstract In the code for nuclear equipment, the elasto-plastic correction factor KE is a correction factor when the stress range exceeds the yield limit for simplified elasto-plastic fatigue analysis. The parameters and expressions of KE for commonly used materials (such as austenitic stainless steel) are given in the RCC-M and ASME code, but the parameters of KE for titanium alloy materials is lacking. Based on the cyclic elasto-plastic constitutive model of Z2CND18.12 (nitrogen control) and KE parameters of austenitic stainless steel given in the code, considering various sensitive factors, a numerical calculation method for determining KE correlation coefficient is established. The elasto-plastic constitutive model of TA16 alloy with nonlinear kinematic hardening was established by the uniaxial tension, strain and stress cycling tests of TA16 titanium alloy. Based on the numerical calculation method of KE and the constitutive model of TA16 titanium alloy, the expression and correlation coefficient of KE for TA16 titanium alloy were determined.

Download Full-text

Precise grading of surrounding rock based on the numerical calculation of the jointed rock mass

Proceedings of the Institution of Civil Engineers - Geotechnical Engineering ◽

10.1680/jgeen.21.00155 ◽

2022 ◽

pp. 1-32

Author(s):

Dan Huang ◽

Xiao-Qing Li ◽

Wen-Chao Song

Keyword(s):

Rock Mass ◽

Numerical Calculation ◽

Calculation Method ◽

Jointed Rock ◽

Jointed Rock Mass ◽

Surrounding Rock ◽

Geological Survey ◽

Survey Method ◽

Synthetic Rock ◽

Numerical Calculation Method

In this study, grading of surrounding rock was based on rock mass basic quality (BQ) values according to the specifications in China. Numerical approach was to construct synthetic rock mass (SRM) model to represent the jointed rock mass, and obtain the strength of the rock mass. It represented intact rock by the bonded particle model (BPM), and represent joint behaviour by the smooth joint model (SJM) to construct the discrete fracture network (DFN). In the Hongtuzhang Tunnel, the micro properties of granite cores with different weathered degrees were determined by the validation process, and the calculation representative elementary volume (REV) of surrounding rock was 15 m×15 m. Five slightly weathered, three slightly to moderately weathered, and two moderately weathered granite surrounding rock mass models were established based on the probability distribution of joint sets in each borehole, the conversion BQ value was acquired according by the calculated strength of rock mass model. It was discussed the differences of surrounding rock grades between the geological survey method and the numerical calculation method, and then found that the geological survey report is higher than the numerical calculation method predicted. And the numerical calculation is consistent with the actual excavation of rock mass at borehole A1388.

Download Full-text

Nanoparticles-Laden Gas Film in Aerostatic Thrust Bearing

Journal of Tribology ◽

10.1115/1.4026503 ◽

2014 ◽

Vol 136 (3) ◽

Cited By ~ 1

Author(s):

Zhiru Yang ◽

Dongfeng Diao ◽

Xue Fan ◽

Hongyan Fan

Keyword(s):

Effective Viscosity ◽

Flow Model ◽

Thrust Bearing ◽

Volume Fraction ◽

Load Capacity ◽

Sio2 Nanoparticles ◽

Enhancement Effect ◽

The Novel ◽

Two Phase ◽

Air Film

Nanoparticles-laden gas film (NLGF) was formed by adding SiO2 nanoparticles with volume fraction in the range of 0.014–0.330% and size of 30 nm into the air gas film in a thrust bearing. An effective viscosity of the gas-solid two phase lubrication media was introduced. The pressure distribution in NLGF and the load capacity of the thrust bearing were calculated by using the gas-solid two phase flow model with the effective viscosity under the film thicknesses range of 15–60 μm condition. The results showed that the NLGF can increase the load capacity when the film thickness is larger than 30 μm. The mechanism of the enhancement effect of load capacity was attributed to the increase of the effective viscosity of the NLGF from the pure air film, and the novel lubrication media of the NLGF can be expected for the bearing industry application.

Download Full-text

A Numerical Investigation of the Effect of Inlet Preswirl Ratio on Rotordynamic Characteristics of Labyrinth Seal

Volume 7A: Structures and Dynamics ◽

10.1115/gt2017-64745 ◽

2017 ◽

Author(s):

Tomohiko Tsukuda ◽

Toshio Hirano ◽

Cori Watson ◽

Neal R. Morgan ◽

Brian K. Weaver ◽

...

Keyword(s):

Flow Model ◽

Three Dimensional ◽

Axial Direction ◽

Labyrinth Seal ◽

Flow Fields ◽

Bulk Flow ◽

The Other ◽

Circumferential Velocity ◽

Stiffness Coefficients ◽

Inlet Swirl

Full three-dimensional CFD simulations are carried out using ANSYS CFX to obtain the detailed flow field and to estimate the rotordynamic coefficients of a labyrinth seal for various inlet swirl ratios. Flow fields in the labyrinth seal with the eccentricity of the rotor are observed in detail and the detailed mechanisms that increase the destabilizing forces at high inlet swirl ratios are discussed based on the fluid governing equations associated with the flow fields. By evaluating the contributions from each term of the governing equation to cross coupled force, it is found that circumferential velocity and circumferential distribution of axial mass flow rate play key roles in generating cross coupled forces. In the case that circumferential velocity is high and decreases along the axial direction, all contributions from each term are positive cross coupled force. On the other hand, in the case that circumferential velocity is low and increases along the axial direction, one contribution is positive but the other is negative. Therefore, cross coupled force can be negative in the local chamber depending on the balance even if circumferential velocity is positive. CFD predictions of cross coupled stiffness coefficients and direct damping coefficients show better agreement with experimental results than a bulk flow model does by considering the force on the rotor in the inlet region. Cross coupled stiffness coefficients derived from the force on the rotor in the seal section agree well with those of the bulk flow model.

Download Full-text

Studies on the Fluidized Bed Electrode

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1610 ◽

2008 ◽

Vol 6 (1) ◽

Cited By ~ 4

Author(s):

Siva Kumar ◽

Thilakavathi Ramamurthy ◽

Bala Subramanian ◽

Ahmed Basha

Keyword(s):

Fluidized Bed ◽

Annular Flow ◽

Flow Model ◽

Model Simulation ◽

Flow Behavior ◽

Hydrodynamic Characteristics ◽

The Core ◽

Particle Transfer ◽

Fluidized Bed Electrode

The present investigation attempts to study the hydrodynamic characteristics of the fluidized bed electrode. A core-annular flow model with a transfer of particles between core-annular layers has been proposed to describe the flow behavior of conducting particles in the fluidized bed electrode. The effect of individual parameters on the rate of the particle transfer across the layer and thickness of the core-annular has been critically examined and the model simulation has been verified with the data reported in the literature.

Download Full-text